1. FIELD OF THE INVENTION
The present invention relates to an electro-acoustic transducer for reproducing sound in either the low, medium, or high frequencies in concert halls, sound studios, home, automobile, and the like in predominantly a non-directional pattern due to the spherical shape of the radiating diaphragm.
2. DESCRIPTION OF THE PRIOR ART
Several known electro-acoustic transducers embody a diaphragm with a spherical shape. However, either owing to a method of obtaining the spherical shape and/or the operating principle for driving the diaphragm, none have achieved acceptable omnidirectional dispersion of the radiated waves, contrary to repeated affirmation of such in numerous claims. U.S. Pat. No. 1,690,726 issued to E. F. Hollinger on Nov. 6, 1928 discloses a loudspeaker having an ovoidially shaped diaphragm driven in a north-south axial direction by an exteriorly located magnetic arrangement. The magnetic unit is comprised of a permanent magnet and an electromagnet which drive the lower segment of the diaphragm. The ovoid diaphragm is comprised of an upper dome shaped diaphragm and a lower cone shaped diaphragm. Each of the diaphragm portions is in itself composed of vertically disposed strip-like segments. The lower section of the diaphragm is connected to a vibrating armature while the upper section of the diaphragm is retained by a rod running from the top of the diaphragm through the armature means to the actuating means. A means that is flexible is used to connect the two halves of the diaphragm together. The operating principle of the loudspeaker requires the upper half remain relatively rigid. The upper half of the diaphragm serves as a wave guide while the lower half acts as the resonant member.
It is quite apparent that unlike the perfect sphere of the present invention which is driven by internally located magnetic arrangement(s), the Hollinger '726 ovoid diaphragm does not achieve acceptable omidirectionality. All sections of the Hollinger '726 diaphragm do not participate in the reproduction of sound. In fact, the presence of an outwardly extending yeildable member connecting the two halves of the diaphragm together prevents air from wrapping around the pear shaped diaphragm during minute movements.
In U.S. Pat. No. 1,653,045 issued to E. F. Hollinger on Dec. 20, 1927, Hollinger teaches a loudspeaker embodying a configuration very similar to Hollinger '726. However, in this later patent, Hollinger incorporates a diaphragm that is a unitary sphere driven in its entirety at its lower end by an actuating means. It is very apparent that the relatively massive sphere of the Hollinger '045 design could not be effectively driven at its lower edge by the actuating means. Nor could the Hollinger '045 speaker produce a true reproduction of sound in an honest omnidirectional capacity.
Yet another of Hollinger's loudspeakers is disclosed by U.S. Pat. No. 1,690,725 issued on Nov. 6, 1928. the Hollinger '725 patent follows the configuration of his '726 loudspeaker. However, the '725 loudspeaker is largely spherical, and the halves are connected by the same yeildable member at the equatorial diameter. The shortcomings of the '726 design are as easily apparent in the '725 version. As a result, it is not necessary to delve into a discourse on the Hollinger '725 shortcomings.
U.S. Pat. No. 1,776,223 issued to J. V. L. Hogan on Sept. 16, 1930 discloses a loudspeaker employing a spherical diaphragm. Due to the means for rigidly securing the radiating diaphragm to a rigid part of the system, and also due to the driving mechanism of the spherical diaphragm via an exteriorly located unit, the diaphragm does not have the freedom of motion to accurately reproduce the motions imparted by the actuating unit. As a result, the loudspeaker can not reproduce sound in a truly omnidirectional capacity. Also, due to the design of this speaker, and the others aforementioned, it can not be reduced in size because of the exteriorly located actuating means. To reiterate, the Hogan and the Hollinger speakers fail to provide good reproducible sound. Moreover, they can not achieve omnidirectional dispersion of sound waves.
U.S. Pat. No. 4,472,605 issued to S. Klein on Sept. 18, 1984 is still another spherical loudspeaker disclosed by the prior art. In the Klein loudspeaker, two hemispherical diaphragms are arranged on either side of a disk shaped carrier part. The diaphragms are connected to these disks by flanges. The connection of these parts results in the formation of a chamber. A magnetic arrangement drives each of the hemispheres via a rigid hemispherical projection attached to the hemispherical diaphragms. The peripheral edge sections of the diaphragms are retained by a yeildable surround exteriorly located and attached to exterior projections of the disc shaped carrier parts. The actuating units are interiorly located.
The Klein loudspeaker does not present a true sphere because the diaphragm halves are not directly connected either flexibly or rigidly. The resultant shape of the diaphragm is an oblate spheroid due to the presence of the peripheral yeildable surrounds, carrier parts, and carrier spacer. The loudspeaker is, indeed, a pair of electrically connected dipoles. The aerodynamics of the resultant shape prevents air from effectively passing through the equator defined by the carrier part. During high acoustic output when the air manages to travel past both the carrier part and the yeildable surround, the net force in the equatorial direction is reduced to a minimum so that acceptable omnidirectional sound dispersion is not achieved. Omnidirectionality is not achieved, because the two diaphragm halves vibrate in opposite directions at right angles to the carrier parts. This creates stationary waves (a combination of two waves of the same strength and frequency traveling in opposite directions) at the equatorial diameter which reduces the acoustic output thereabout. Tests on such loudspeakers as the Klein design have proven this finding to be correct. It has been observed that the relatively large hemispherical projections driving the diaphragms substantially increases the overall weight of the moving members and reduces the sensitivity of the entire system.
U.S. Pat. No. 4,550,797 issued to Suzuki on Nov. 5, 1985 presents a dome shaped loudspeaker diaphragm having a molded sintered ceramic body having an outwardly extending peripheral flange. This prior invention must not be confused with the open apex hemispheres comprising the spherically shaped diaphragm of the present invention. The present invention further differs from the Suzuki diaphragm design in that the peripheral edge flanges are inwardly extending. The inwardly extending edge flange permits spherical alignment at the equatorial diameter.
U.S. Pat. No. 2,846,520 issued to P. J. Brownscombe on Aug. 5, 1958 presents a loudspeaker having magnetic arrangements housed behind a dome shaped diaphragm. Brownscombe utilizes the dome shaped diaphragm to increase the angle of dispersion of sound. Brownscombe discloses in U.S. Pat. No. 2,846,520 some modifications of his earlier designs. This Brownscombe design, in addition to his prior concepts, differ completely from the present invention both in function and assemblage.